Thread grinding machine



July 31, 1945. F. TURRETTINI I 2,

THREAD GRINDING MACHINE Filed May 8, 1944 I 2 Sheets -Sheet l K I v\ 0 g w v M EL v m g! I 5 "q 0 4 D li a" 7 im/ &(l I

' IIZ1U1ZZO.ZB

I. T wrretbzip/v July 31,1945- F. TURRETTINI I 5 5 THREAD GRINDING MACHINE Filed May 8, 1944 2 Sheets-Sheet 2 Inventor Patented July 31, 19 45 UNITED" ST TE mam OFFICE mnancamnnvouaonmn ortosociete lmiaae aerlaad pplication Kay 8,

' two abutments determining two positions of the table: one for the grinding oi the work piece and the other for the truing of th grinding wheel.

' According to the invention, this machine is characterized by an auxiliary slide arranged movably on the bed, and inserted between the nut and one of the abutments mentioned above, by a system of two unequal counterweig'hts exerting their action in opposite directions on the auxiliary slide, and by lifting means enabling to temporarily remove the action or th heavier counterweight on the auxiliary slide, the whole being arranged in such a manner that the action of the counterweights either maintains the auxiliary slide in contact with the first abutment during the grinding operation or brings the table into contact with, the second abutment for truing the grinding wheel.

The annexed drawings" represent by way or example an embodiment of the invention. Fig. 1 is a sectional elevation and Fig. 2a transverse] section. Fig. 3 is a view in perspective in which the table, as well as the front face oi the bed have been omitted in order to show the mechanism.

In any of these figures I lathe table movable on the guide ways 2' and Ila of the bed 6. 2 is the spindle and Is the headstock, I'the tailstock, I the truing device. I the grinding wheel, i the bed and I the abutment fixed to the bed, which determines the truing position .of the table; I is a train of reduction gears connecting th spindle to the lead-screw 9; II and lid are the lead-screw bearings, II 'is the lead-screw nut. and I! an auxiliary slide: it is a groove in the bed for guiding the auxiliary slide-i2. I4 is the face of the nut II which bears against two brackets it and "a dependent on the auxiliary slldeimd located on each side oi the lead-screw 9. It and lid are, two lateral trunnions of the nut M to which are attached the cables I! and it passing over the pulleys i1 and "a. These cables are supporting the first counterweight ii, the heavier out of the two. II is a cable used for lifting the counterweight I! and being wound-up on a winding drum 2i by means of a handle 22. It is the abutment of the bed, determining the grinding position of the table, abutment against which the auxiliary slide i1 comes to rest under the action of the counterweight II during the grinding operation; II are brackets forming part of 23 and bearing the pulleys l1 and "a. 24 are the bolts for flxing'oi' II on the bed i. "is the cable connecting the auxiliary slide it to the second coun- 'Fernand 'lurrettini, Geneva, swltaerland, lllsn- Genevoise i Geneva; Switaerland, a am of Switdlmiramen 1944, Serial No. 534,584 November- 27, 1M8

terwelght 21 (the less heavy out of the two), by passing over the pulley ll. SI is a liner dependenton the nut ii and col g in a recess ii of the auxiliary slide it, this in order to prevent said nutfrom rotating. This nut it could be maintained in position by using other means-to prevent it from rotation. when the grinding work is being performed. all the parts are in the position shown on the drawings.

I: truing of the grinding wheel is required, the counterweight I! attached to the cable II has to beliftedbymeans oi thewindingdrum 2i and the handle 22. In this case the counterweight 21 is going to pull the auxiliary slide i2 towards the left, which, in its turn, will move the table towards the left, by means of the parts II and i, and this until the table comes into contact I. Now the trulng device 4 will be in the working position in front of the grinding wheel I.

This operation may be carried out very rapidly by giving the handle 22 a few turns. This handle must be immobilised by means not represented in the drawings, when the coimterweight is is supported by the winding drum ii, in order to prevent the lowering oi the counterweight is before the truing of the grinding wheel is completed.

Obviously it is of importance to reduce to a minimum the friction of the auxiliary slide i2 and of the table i on the bed I in order to decrease the necessary weight difference between the counterweights I! and 21. This purpose can be achieved either by arrangi g the table to rest on a few points it only on the slideways or the bed, or by making it roll on these slideways.

What I claim is:

In a thread grinding machine with a work piece carrying table supporting a device for truing the grinding wheel and being operated by means or a lead-screw cooperating with a. nut, the bed of the machine comprising two abutments determining two positions'of the table: one for the grinding of the work piece and the other for the truing oi the grinding wheel, in combination, an auxiliary slide arranged movably on the bed and inserted between the nut and one of the abutments, a system with 

